Games with rapid release cycles often seem to give up on getting into the official repos and entirely rely on PPAs. SpringRTS is also conspicuously absent, but its lack of single-player content might explain that too.

Yes, that should have been in there. It's one of those games where it has a package version tacked onto the package name.. (ie; wesnoth-1.10).. So the total installs of wesnoth gets divided on all the different versions of it and that throws off my searches as I didn't have an easy way to correlate the packages. The sum of the people with the different wesnoth packages across Debian and Ubuntu is quite high, but it gets divided as not everybody installs the wesnoth meta package or the same package version of it (ie: wesnoth-1.8, wesnoth-1.9, wesnoth-1.10, etc.).

Certainly my methods for generating the list are far from perfect :(. But I think it's not too bad.

Xonotic is a direct successor of the Nexuiz project. It represents years of development from its humble beginnings as a Quake 1 engine modification, and now aims to be the best possible open source first person shooter available. It could be considered most similar to Unreal Tournament and Quake at its heart, especially regarding teamplay and game mechanics.

The game was developed as a fork of Nexuiz, following controversy surrounding the game's development.

Xonotic IS Nexuiz. original author of Nexuiz sell this trademark to some company. they created new nexuiz based on unreal engine which you can buy on steam. so Xonotic is continuation of original Nexuiz.

*since the parent comment got deleted, i'll give the gist of what was said: That Frogatto is weird since its code is open source, but not its assets. and there was a link to the frogatto source page: http://www.frogatto.com/source

How is that weird? Isn't that how id software does it as well (and to some extent, firefox)?

Seems perfectly reasonable to me and I think if people thought of this as the norm we'd see more games with protagonist that aren't penguins.

First of all, the GPL doesn't remove the copyright. It enforces it. The copyright stays with the creator and the GPL (or other OSS licenses) make it easy for the copyright-holder to give you terms on how you can use the copyrighted work. You can check pretty much every GPL'd work ("this copyrighted work is licensed under the GNU General Public License".. or CC or whatever).

Secondly, if Frogattos assets where "unfree" they wouldn't be in Debian. So there's that.